Devices, Systems, and Methods for Vessel Assessment

ABSTRACT

Devices, systems, and methods for visually depicting a vessel and evaluating a physiological condition of the vessel are disclosed. One embodiment includes obtaining, at a first time, a first image of the vessel, the image being in a first medical modality, and obtaining, at a second time subsequent to the first time, a second image of the vessel, the image being in the first medical modality. The method also includes spatially co-registering the first and second images and outputting a visual representation of the co-registered first and second images on a display. Further, the method includes determining a physiological difference between the vessel at the first time and the vessel at the second time based on the co-registered first and second images, and evaluating the physiological condition of the vessel of the patient based on the determined physiological difference.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to and the benefit of the U.S.Provisional Patent Application No. 61/989,219, filed May 6, 2014, whichis hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to the assessment of vesselsand, in particular, the assessment of physiological changes in vesselsover time. Aspects of the present disclosure are particularly suited forevaluation of biological vessels in some instances. For example, someparticular embodiments of the present disclosure are specificallyconfigured for the evaluation of a stenosis of a human blood vessel.

BACKGROUND

A currently accepted technique for assessing the severity of a stenosisin a blood vessel, including ischemia causing lesions, is fractionalflow reserve (FFR). FFR is a calculation of the ratio of a distalpressure measurement (taken on the distal side of the stenosis) relativeto a proximal pressure measurement (taken on the proximal side of thestenosis). FFR provides an index of stenosis severity that allowsdetermination as to whether the blockage limits blood flow within thevessel to an extent that treatment is required. The normal value of FFRin a healthy vessel is 1.00, while values less than about 0.80 aregenerally deemed significant and require treatment. Common treatmentoptions include percutaneous coronary intervention (PCI or angioplasty),stenting, or coronary artery bypass graft (CABG) surgery. As with allmedical procedures, certain risks are associated with PCI, stenting, andCABG procedures. In order for a surgeon to make a better-informeddecision regarding treatment options, additional information about therisk and likelihood of success associated with the treatment options isneeded.

Additionally, numerical calculations such as FFR are used to track theeffectiveness of an intravascular procedure, such as the insertion of astent in a vessel. Typically, to evaluate the effectiveness of anintravascular procedure, a practitioner will conduct a longitudinalstudy over a time period that encompasses the procedure. For example,FFR calculations may be performed before and after an intravascularprocedure to track the improvement of the patient. However, suchnumerical-based longitudinal studies are less than ideal because theyrequire a practitioner to perform mental estimations about anyphysiological changes in the vessel.

Accordingly, there remains a need for improved devices, systems, andmethods for assessing physiological changes in a vessel over time.

SUMMARY

Embodiments of the present disclosure are configured to assessphysiological changes in a vessel over time. In some particularembodiments, the devices, systems, and methods of the present disclosureare configured to provide co-registered visual depictions of a vessel atdifferent points in time that allow assessment of changes in the vessel.Further, in some embodiments, the devices, systems, and methods of thepresent disclosure are configured to provide co-registered visualdepictions of a vessel in different imaging modalities that facilitateassessment of the vessel over a time period.

In one embodiment, a method of evaluating a vessel of a patient isprovided. The method includes obtaining, at a first time, a firstgraphical diagnostic measurement of the vessel of the patient, the firstgraphical diagnostic measurement being in a first medical modality, andobtaining, at a second time subsequent to the first time, a secondgraphical diagnostic measurement of the vessel, the graphical diagnosticmeasurement being in the first medical modality. The method alsoincludes spatially co-registering the first and second graphicaldiagnostic measurements, and outputting a visual representation of theco-registered first and second graphical diagnostic measurements on adisplay. Additionally, the method includes determining a physiologicaldifference between the vessel at the first time and the vessel at thesecond time based on the co-registered first and second graphicaldiagnostic measurements, and evaluating the physiological condition ofthe vessel of the patient based on the determined physiologicaldifference.

In another embodiment, a second method of evaluating a vessel of apatient is disclosed. The method includes obtaining, at a first time, afirst graphical diagnostic measurement of the vessel, the firstgraphical diagnostic measurement being in a first medical imagingmodality, and obtaining, at the first time, a second graphicaldiagnostic measurement of the vessel, the second graphical diagnosticmeasurement being in a second medical imaging modality different thanthe first medical imaging modality. The method also includes obtaining,at a second time, a third graphical diagnostic measurement of thevessel, the third graphical diagnostic measurement being in the firstmedical imaging modality, and obtaining, at the second time, a fourthgraphical diagnostic measurement of the vessel, the fourth graphicaldiagnostic measurement being in the second medical imaging modality.Additionally, the method includes spatially co-registering the first andthird graphical diagnostic measurements, spatially co-registering thesecond and fourth graphical diagnostic measurements, and spatially andtemporally co-registering the first and second graphical diagnosticmeasurements. The method further includes outputting a visualrepresentation of the co-registered first, second, third, and fourthgraphical diagnostic measurements on a display, and determining aphysiological difference between the vessel at the first time and thevessel at the second time based on at least one of the co-registeredfirst and third graphical diagnostic measurements and the co-registeredsecond and fourth graphical diagnostic measurements. The method alsoincludes evaluating the physiological condition of the vessel based onthe determined physiological difference.

In yet another embodiment, a system of evaluating a vessel of a patientis disclosed. The system includes an instrument configured to obtaingraphical diagnostic measurements of the vessel of the patient and aprocessing system in communication with the first instrument. Theprocessing unit is configured to obtain, at a first time, a firstgraphical diagnostic measurement of the vessel from the instrument, thefirst graphical diagnostic measurement being in a first medical modalityand obtain, at a second time subsequent to the first time, a secondgraphical diagnostic measurement of the vessel from the instrument, thegraphical diagnostic measurement being in the first medical modality.The processing unit is also configured to spatially co-register thefirst and second graphical diagnostic measurements and output a visualrepresentation of the co-registered first and second graphicaldiagnostic measurements on a display. Additionally, the processing unitis configured to determine a physiological difference between the vesselat the first time and the vessel at the second time based on theco-registered first and second graphical diagnostic measurements, andevaluate the physiological condition of the vessel of the patient basedon the determined physiological difference

Additional aspects, features, and advantages of the present disclosurewill become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the present disclosure will be describedwith reference to the accompanying drawings, of which:

FIG. 1 is a schematic drawing depicting a medical system including amulti-modality processing system according to one embodiment of thepresent disclosure.

FIG. 2 is a diagrammatic perspective view of a vessel having a stenosisaccording to an embodiment of the present disclosure.

FIG. 3 is a diagrammatic, partial cross-sectional perspective view of aportion of the vessel of FIG. 2 taken along section line 3-3 of FIG. 2.

FIG. 4 is a diagrammatic, schematic view of a medical system accordingto an embodiment of the present disclosure.

FIGS. 5-8 are stylized images of a portion of a patient's vasculatureaccording to embodiments of the present disclosure.

FIG. 9 illustrates a simplified flow chart of a method of assessing thecondition of a vessel over time, according to embodiments of the presentdisclosure.

FIG. 10 illustrates a graphical user interface (GUI) screen configuredto facilitate the multi-modality assessment of a patient's vasculatureover time, according to aspects of the present disclosure.

FIG. 11 illustrates a simplified flow chart of a method for assessingthe condition of a vessel over time, according to another embodiment ofthe present disclosure.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of thepresent disclosure, reference will now be made to the embodimentsillustrated in the drawings, and specific language will be used todescribe the same. It is nevertheless understood that no limitation tothe scope of the disclosure is intended. Any alterations and furthermodifications to the described devices, systems, and methods, and anyfurther application of the principles of the present disclosure arefully contemplated and included within the present disclosure as wouldnormally occur to one skilled in the art to which the disclosurerelates. In particular, it is fully contemplated that the features,components, and/or steps described with respect to one embodiment may becombined with the features, components, and/or steps described withrespect to other embodiments of the present disclosure. For the sake ofbrevity, however, the numerous iterations of these combinations will notbe described separately.

FIG. 1 is a schematic drawing depicting a medical system 100 including amulti-modality processing system 101 according to one embodiment of thepresent disclosure. In general, the medical system 100 provides forcoherent integration and consolidation of multiple forms of acquisitionand processing elements designed to be sensitive to a variety of methodsused to acquire and interpret human biological physiology andmorphological information. More specifically, in system 100, themulti-modality processing system 101 is an integrated device for theacquisition, control, interpretation, and display of multi-modalitymedical data. In one embodiment, the processing system 101 is a computersystem with the hardware and software to acquire, process, and displaymulti-modality medical data, but, in other embodiments, the processingsystem 101 may be any other type of computing system operable to processmedical sensing data. In the embodiments in which processing system 101is a computer workstation, the system includes at least a processor suchas a microcontroller or a dedicated central processing unit (CPU), anon-transitory computer-readable storage medium such as a hard drive,random access memory (RAM), and/or compact disk read only memory(CD-ROM), one or more video controllers such as a graphics processingunit (GPU), and a network communication device such as an Ethernetcontroller. In that regard, in some particular instances the processingsystem 101 is programmed to execute steps associated with the dataacquisition, analysis, and co-registration described herein.Accordingly, it is understood that any steps related to dataacquisition, data processing, instrument control, and/or otherprocessing or control aspects of the present disclosure may beimplemented by the processing system using corresponding instructionsstored on or in a non-transitory computer readable medium accessible bythe processing system. In some instances, the processing system 101 is aconsole computing device. In some particular instances, the processingsystem 101 is similar to the s5™ Imaging System, the s5i™ ImagingSystem, or other imaging systems available from Volcano Corporation. Insome instances, the processing system 101 is portable (e.g., handheld,on a rolling cart, etc.). Further, it is understood that in someinstances processing system 101 comprises a plurality of computingdevices. In that regard, it is particularly understood that thedifferent processing and/or control aspects of the present disclosuremay be implemented separately or within predefined groupings using aplurality of computing devices. Any divisions and/or combinations of theprocessing and/or control aspects described below across multiplecomputing devices are within the scope of the present disclosure.

In the illustrated embodiment, the medical system 100 is deployed in acatheter lab 102 having a control room 104, with the processing system101 being located in the control room. In other embodiments, theprocessing system 101 may be located elsewhere, such as in the catheterlab 102, in a centralized area in the medical facility, or at anoff-site location. The catheter lab 102 includes a sterile field but itsassociated control room 104 may or may not be sterile depending on therequirements of a procedure and/or health care facility. The catheterlab and control room may be used to perform on a patient any number ofmedical procedures such as angiography, intravascular ultrasound (IVUS),virtual histology (VH), forward looking IVUS (FL-IVUS), intravascularphotoacoustic (IVPA) imaging, near-infrared Spectroscopy (NIRS), afractional flow reserve (FFR) determination or other pressure-baseddetermination (e.g., iFR), a coronary flow reserve (CFR) determination,optical coherence tomography (OCT), intravascular OCT, computedtomography (CT), intracardiac echocardiography (ICE), forward-lookingICE (FLICE), intravascular palpography, transesophageal ultrasound, orany other medical sensing modalities known in the art. Further, thecatheter lab and control room may be used to perform one or moretreatment or therapy procedures on a patient such as radiofrequencyablation (RFA), cryotherapy, atherectomy, stenting, or any other medicaltreatment procedure known in the art. For example, in catheter lab 102 apatient 106 may be undergoing a multi-modality procedure either as asingle procedure or in combination with one or more sensing procedures.In any case, the catheter lab 102 includes a plurality of medicalinstruments including medical sensing devices that may collect medicalsensing data in various different medical sensing modalities from thepatient 106.

Instruments 108 and 110 are medical sensing devices that may be utilizedby a clinician to acquire medical sensing data about the patient 106. Ina particular instance, the device 108 collects medical sensing data inone modality and the device 110 collects medical sensing data in adifferent modality. For instance, the instruments may each collect oneof pressure, flow (velocity), images (including images obtained usingultrasound (e.g., IVUS), OCT, IVPA, intravascular MRI, thermal, ICE,Trans Esophageal Echo (TEE), Trans Thoracic Echo (TTE) and/or otherinternal imaging techniques), temperature, and/or combinations thereof.The instruments 108 and 110 may be any form of device, instrument, orprobe sized and shaped to be positioned within a vessel, attached to anexterior of the patient, or scanned across a patient at a distance.

In the illustrated embodiment of FIG. 1, instrument 108 is anintravascular IVUS catheter that may include one or more sensors such asa phased-array transducer to collect IVUS sensing data. In someembodiments, the IVUS catheter may be capable of multi-modality sensingsuch as IVUS and IVPA sensing. Further, in the illustrated embodiment,the instrument 110 is an intravascular OCT catheter that may include oneor more optical sensors configured to collect OCT sensing data. In afurther embodiment, a single instrument incorporates aspects of thefunctionalities (e.g., data acquisition) of both instruments 108 and110. In the illustrated embodiment of FIG. 1, an IVUS patient interfacemodule (PIM) 112 and an OCT PIM 114 respectively couple the instrument108 and instrument 110 to the medical system 100. In particular, theIVUS PIM 112 and the OCT PIM 114 are operable to respectively receivemedical sensing data collected from the patient 106 by the instrument108 and instrument 110 and are operable to transmit the received data tothe processing system 101 in the control room 104. In one embodiment,the PIMs 112 and 114 include analog to digital (A/D) converters andtransmit digital data to the processing system 101, however, in otherembodiments, the PIMs transmit analog data to the processing system. Inone embodiment, the IVUS PIM 112 and OCT PIM 114 transmit the medicalsensing data over a Peripheral Component Interconnect Express (PCIe)data bus connection, but, in other embodiments, they may transmit dataover a USB connection, a Thunderbolt connection, a FireWire connection,or some other high-speed data bus connection. In other instances, thePIMs may be connected to the processing system 101 via wirelessconnections using IEEE 802.11 Wi-Fi standards, Ultra Wide-Band (UWB)standards, wireless FireWire, wireless USB, or another high-speedwireless networking standard. In further embodiments, the connectionhardware and functionality of the PIMs 112 and 114 is implemented in asingle PIM that is coupled to both of instruments 108 and 110.

Additionally, in the medical system 100, an electrocardiogram (ECG)device 116 is operable to transmit electrocardiogram signals or otherhemodynamic data from patient 106 to the processing system 101. In someembodiments, the processing system 101 may be operable to synchronizedata collected with the instruments 108 and 110 using ECG signals fromthe ECG 116. Further, an external imaging system 117 is operable tocollect x-ray images, angiogram images, ultrasound images, two orthree-dimensional computed tomography (CT) images, computed tomographyangiogram (CTA) images, positron emission tomography (PET) images,PET-CT images, magnetic resonance images (MRI), single-photon emissioncomputed tomography (SPECT) images, and/or any combination of the aboveimages of the patient 106 and transmit them to the processing system101. In one embodiment, the external imaging system 117 may becommunicatively coupled to the processing system to the processingsystem 101 through an adapter device. Such an adaptor device maytransform data from a proprietary third-party format into a formatusable by the processing system 101. As will be explained in greaterdetail below, in some embodiments, the processing system 101 may beoperable to co-register image data from external imaging system 117(e.g., x-ray data, MRI data, CT data, etc.) with sensing data from theinstruments 108 and 110 and other instruments internal and external tothe catheter lab. As one aspect of this, the co-registration may beperformed to generate three-dimensional images with the sensing data. Inanother embodiment, medical data from the ECG and/or external imagingsystem 117 may be temporally co-registered with medical data captured byeither of (or both) instruments 108 and 110. Spatial and temporalco-registration will be discussed in greater detail in association withFIGS. 5-11.

A bedside controller 118 is also communicatively coupled to theprocessing system 101 and provides user control of the particularmedical modality (or modalities) being used to diagnose the patient 106.In the current embodiment, the bedside controller 118 is a touch screencontroller that provides user controls and diagnostic images on a singlesurface. In alternative embodiments, however, the bedside controller 118may include both a non-interactive display and separate controls such asphysical buttons and/or a joystick. In the integrated medical system100, the bedside controller 118 is operable to present workflow controloptions and patient image data in graphical user interfaces (GUIs). Thebedside controller 118 is capable displaying workflows and diagnosticimages for multiple modalities allowing a clinician to control theacquisition of multi-modality medical sensing data with a singleinterface device.

A main controller 120 in the control room 104 is also communicativelycoupled to the processing system 101 and, as shown in FIG. 1, isadjacent to catheter lab 102. In the current embodiment, the maincontroller 120 is similar to the bedside controller 118 in that itincludes a touch screen and is operable to display a multitude ofGUI-based workflows corresponding to different medical sensingmodalities via a UI framework service executing thereon. In someembodiments, the main controller 120 may be used to simultaneously carryout a different aspect of a procedure's workflow than the bedsidecontroller 118. In alternative embodiments, the main controller 120 mayinclude a non-interactive display and standalone controls such as amouse and keyboard.

The medical system 100 further includes a boom display 122communicatively coupled to the processing system 101. The boom display122 may include an array of monitors, each capable of displayingdifferent information associated with a medical sensing procedure. Forexample, during an IVUS procedure, one monitor in the boom display 122may display a tomographic view and one monitor may display a sagittalview.

Further, in some embodiments, the multi-modality processing system 101is communicatively coupled to a data network such as a TCP/IP-basedlocal area network (LAN), a Synchronous Optical Networking (SONET)network, or a wide area network (WAN) or the Internet. The processingsystem 101 may connect to various resources via such a network. Forexample, the processing system 101 may communicate with a DigitalImaging and Communications in Medicine (DICOM) system, a PictureArchiving and Communication System (PACS), and a Hospital InformationSystem (HIS) through the network.

Additionally, in the illustrated embodiment, medical instruments insystem 100 discussed above are shown as communicatively coupled to theprocessing system 101 via a wired connection such as a standard copperlink or a fiber optic link, but, in alternative embodiments, the toolsmay be connected to the processing system 101 via wireless connectionsusing IEEE 802.11 Wi-Fi standards, Ultra Wide-Band (UWB) standards,wireless FireWire, wireless USB, or another high-speed wirelessnetworking standard.

One of ordinary skill in the art would recognize that the medical system100 described above is simply an example embodiment of a system that isoperable to collect diagnostic data associated with a plurality ofmedical modalities. In alternative embodiments, different and/oradditional tools may be communicatively coupled to the processing system101 so as to contribute additional and/or different functionality to themedical system 100.

Referring to FIG. 2, shown therein is a vessel 124 having a stenosisaccording to an embodiment of the present disclosure. In that regard,FIG. 2 is a diagrammatic perspective view of the vessel 124 thatincludes a proximal portion 125 and a distal portion 126. A lumen 127extends along the length of the vessel 124 between the proximal portion125 and the distal portion 126. In that regard, the lumen 127 isconfigured to allow the flow of fluid through the vessel. In someinstances, the vessel 124 is a systemic blood vessel. In some particularinstances, the vessel 124 is a coronary artery. In such instances, thelumen 127 is configured to facilitate the flow of blood through thevessel 124.

As shown, the vessel 124 includes a stenosis 128 between the proximalportion 125 and the distal portion 126. Stenosis 128 is generallyrepresentative of any blockage or other structural arrangement thatresults in a restriction to the flow of fluid through the lumen 127 ofthe vessel 124. Embodiments of the present disclosure are suitable foruse in a wide variety of vascular applications, including withoutlimitation coronary, peripheral (including but not limited to lowerlimb, carotid, and neurovascular), renal, and/or venous. Where thevessel 124 is a blood vessel, the stenosis 128 may be a result of plaquebuildup, including without limitation plaque components such as fibrous,fibro-lipidic (fibro fatty), necrotic core, calcified (dense calcium),blood, fresh thrombus, and mature thrombus. Generally, the compositionof the stenosis will depend on the type of vessel being evaluated. Inthat regard, it is understood that the concepts of the presentdisclosure are applicable to virtually any type of blockage or othernarrowing of a vessel that results in decreased fluid flow.

Note that the stenosis 128 is exemplary in nature and should not beconsidered limiting in any way. In that regard, it is understood thatthe stenosis 128 has other shapes and/or compositions that limit theflow of fluid through the lumen 127 in other instances. While the vessel124 is illustrated in FIG. 2 as having a single stenosis 128 and thedescription of the embodiments below is primarily made in the context ofa single stenosis, it is nevertheless understood that the devices,systems, and methods described herein have similar application for avessel having multiple stenosis regions.

Referring now to FIG. 3, illustrated is a partial cross-sectionalperspective view of a portion of the vessel 124 taken along section line3-3 of FIG. 2. In particular, the vessel 124 is shown with instruments130 and 132 positioned therein according to an embodiment of the presentdisclosure. In general, instruments 130 and 132 may be any form ofdevice, instrument, or probe sized and shaped to be positioned within avessel. In that regard, in some instances instrument 132 is suitable foruse as at least one of instruments 108 and 110 discussed above.Accordingly, in some instances the instrument 132 includes featuressimilar to those discussed above with respect to instruments 108 and 110in some instances. In the illustrated embodiment, instrument 130 isgenerally representative of a guide wire, while instrument 132 isgenerally representative of a catheter. In that regard, instrument 130extends through a central lumen of instrument 132. However, in otherembodiments, the instruments 130 and 132 take other forms. In thatregard, the instruments 130 and 132 are of similar form in someembodiments. For example, in some instances, both instruments 130 and132 are guide wires. In other instances, both instruments 130 and 132are catheters. On the other hand, the instruments 130 and 132 are ofdifferent form in some embodiments, such as the illustrated embodiment,where one of the instruments is a catheter and the other is a guidewire. Further, in some instances, the instruments 130 and 132 aredisposed coaxial with one another, as shown in the illustratedembodiment of FIG. 3. In other instances, one of the instruments extendsthrough an off-center lumen of the other instrument. In yet otherinstances, the instruments 130 and 132 extend side-by-side. In someparticular embodiments, at least one of the instruments is as arapid-exchange device, such as a rapid-exchange catheter. In suchembodiments, the other instrument is a buddy wire or other deviceconfigured to facilitate the introduction and removal of therapid-exchange device. Further still, in other instances, instead of twoseparate instruments 130 and 132 a single instrument is utilized. Inthat regard, the single instrument incorporates aspects of thefunctionalities (e.g., data acquisition) of both instruments 130 and 132in some embodiments.

Instrument 130 is configured to obtain medical diagnostic information(data) about the vessel 124. In that regard, the instrument 130 includesone or more sensors, transducers, and/or other monitoring elementsconfigured to obtain the diagnostic information about the vessel. Thediagnostic information includes one or more of pressure, flow(velocity), images (including images obtained using ultrasound (e.g.,IVUS, IVPA, etc.), intravascular OCT, near-infrared Spectroscopy (NIRS),intravascular MRI, thermal, and/or other endoluminal imagingtechniques), temperature, and/or combinations thereof. The one or moresensors, transducers, and/or other monitoring elements are positionedadjacent a distal portion of the instrument 130 in some instances. Inthat regard, the one or more sensors, transducers, and/or othermonitoring elements are positioned less than 30 cm, less than 10 cm,less than 5 cm, less than 3 cm, less than 2 cm, and/or less than 1 cmfrom a distal tip 134 of the instrument 130 in some instances. In someinstances, at least one of the one or more sensors, transducers, and/orother monitoring elements is positioned at the distal tip of theinstrument 130.

The instrument 130 may include at least one element configured tomonitor pressure within the vessel 124. The pressure monitoring elementcan take the form a piezo-resistive pressure sensor, a piezo-electricpressure sensor, a capacitive pressure sensor, an electromagneticpressure sensor, a fluid column (the fluid column being in communicationwith a fluid column sensor that is separate from the instrument and/orpositioned at a portion of the instrument proximal of the fluid column),an optical pressure sensor, and/or combinations thereof. In someinstances, one or more features of the pressure monitoring element areimplemented as a solid-state component manufactured using semiconductorand/or other suitable manufacturing techniques. Examples of commerciallyavailable guide wire products that include suitable pressure monitoringelements include, without limitation, the PrimeWire PRESTIGE® pressureguide wire, the PrimeWire® pressure guide wire, and the ComboWire® XTpressure and flow guide wire, each available from Volcano Corporation,as well as the PressureWire™ Certus guide wire and the PressureWire™Aeris guide wire, each available from St. Jude Medical, Inc. Generally,the instrument 130 is sized such that it can be positioned through thestenosis 128 without significantly impacting fluid flow across thestenosis, which would impact the distal pressure reading. Accordingly,in some instances the instrument 130 has an outer diameter of 0.018″ orless. In some embodiments, the instrument 130 has an outer diameter of0.014″ or less.

Instrument 132 is also configured to obtain diagnostic information aboutthe vessel 124. In some instances, instrument 132 is configured toobtain the same diagnostic information as instrument 130. In otherinstances, instrument 132 is configured to obtain different diagnosticinformation than instrument 130, which may include additional diagnosticinformation, less diagnostic information, and/or alternative diagnosticinformation. The medical diagnostic information (data) obtained byinstrument 132 includes one or more of pressure, flow (velocity), images(including images obtained using ultrasound (e.g., IVUS, IVPA, etc.),intravascular OCT, NIRS, intravascular MRI, thermal, and/or otherendoluminal imaging techniques), temperature, and/or combinationsthereof. Instrument 132 includes one or more sensors, transducers,and/or other monitoring elements configured to obtain this diagnosticinformation. In that regard, the one or more sensors, transducers,and/or other monitoring elements are positioned adjacent a distalportion of the instrument 132 in some instances. In that regard, the oneor more sensors, transducers, and/or other monitoring elements arepositioned less than 30 cm, less than 10 cm, less than 5 cm, less than 3cm, less than 2 cm, and/or less than 1 cm from a distal tip 136 of theinstrument 132 in some instances. In some instances, at least one of theone or more sensors, transducers, and/or other monitoring elements ispositioned at the distal tip of the instrument 132.

Similar to instrument 130, instrument 132 may also include at least oneelement configured to monitor pressure within the vessel 124. Thepressure monitoring element can take the form a piezo-resistive pressuresensor, a piezo-electric pressure sensor, a capacitive pressure sensor,an electromagnetic pressure sensor, a fluid column (the fluid columnbeing in communication with a fluid column sensor that is separate fromthe instrument and/or positioned at a portion of the instrument proximalof the fluid column), an optical pressure sensor, and/or combinationsthereof. In some instances, one or more features of the pressuremonitoring element are implemented as a solid-state componentmanufactured using semiconductor and/or other suitable manufacturingtechniques. Millar catheters are utilized in some embodiments. Currentlyavailable catheter products suitable for use with one or more ofPhilips's Xper Flex Cardio Physiomonitoring System, GE's Mac-Lab XT andXTi hemodynamic recording systems, Siemens's AXIOM Sensis XP VC11,McKesson's Horizon Cardiology Hemo, and Mennen's Horizon XVu HemodynamicMonitoring System and include pressure monitoring elements can beutilized for instrument 132 in some instances.

In accordance with some aspects of the present disclosure, at least oneof the instruments 130 and 132 may be configured to monitor a pressurewithin the vessel 124 distal of the stenosis 128 and at least one of theinstruments 130 and 132 may be configured to monitor a pressure withinthe vessel proximal of the stenosis. In that regard, the instruments130, 132 are sized and shaped to allow positioning of the at least oneelement configured to monitor pressure within the vessel 124 to bepositioned proximal and/or distal of the stenosis 128 as necessary basedon the configuration of the devices. In that regard, FIG. 3 illustratesa position 138 suitable for measuring pressure distal of the stenosis128. In that regard, the position 138 is less than 5 cm, less than 3 cm,less than 2 cm, less than 1 cm, less than 5 mm, and/or less than 2.5 mmfrom the distal end of the stenosis 128 (as shown in FIG. 2) in someinstances. FIG. 3 also illustrates a plurality of suitable positions formeasuring pressure proximal of the stenosis 128. In that regard,positions 140, 142, 144, 146, and 148 each represent a position that issuitable for monitoring the pressure proximal of the stenosis in someinstances. In that regard, the positions 140, 142, 144, 146, and 148 arepositioned at varying distances from the proximal end of the stenosis128 ranging from more than 20 cm down to about 5 mm or less. Generally,the proximal pressure measurement will be spaced from the proximal endof the stenosis. Accordingly, in some instances, the proximal pressuremeasurement is taken at a distance equal to or greater than an innerdiameter of the lumen of the vessel from the proximal end of thestenosis. In the context of coronary artery pressure measurements, theproximal pressure measurement is generally taken at a position proximalof the stenosis and distal of the aorta, within a proximal portion ofthe vessel. However, in some particular instances of coronary arterypressure measurements, the proximal pressure measurement is taken from alocation inside the aorta. In other instances, the proximal pressuremeasurement is taken at the root or ostium of the coronary artery.

In one embodiment, the instrument 132 includes both a pressure sensorand an imaging sensor, such as an IVUS, IVPA, OCT, NIRS, or MRI senor.In such an embodiment, the plurality of sensors disposed on theinstruments 130 and 132 may be utilized to perform a multi-modalitydiagnostic and/or treatment procedure. For example, the pressure sensordisposed on instrument 130 and the pressure sensor disposed oninstrument 132 may collect medical data for an FFR calculation, and theimaging sensor disposed on instrument 132 may collect medical data to beprocessed into diagnostic images to be displayed to a practitionerand/or analyzed in an automated manner by the processing system 101. Aswill be discussed below in greater detail, pressure data and diagnosticimage data collected over a time period may be co-registered in variousmanners to enable physiological evaluation of a patient's vessel overthe time period. In one embodiment, pressure data and diagnostic imagedata are collected both before and after a medical procedure (such as astent placement or a non-invasive drug treatment) and co-registeredtemporally and spatially to facilitate accurate evaluation of apatient's physiological response to the procedure. Such temporal andspatial co-registration techniques may utilize any type of collectedmedical data discussed herein, including OCT data, angiogram data, MRIdata, intravascular MRI data, FFR data, IVUS data, VH data, FL-IVUSdata, IVPA data, CFR data, CT data, PET data, SPECT data, ICE data,FLICE data, intravascular palpography data, transesophageal ultrasounddata, or any other medical data known in the art.

Additionally, the instruments 130 and 132 may be sized and shaped toallow concurrent positioning of additional catheter-type instrumentswithin the vessel 124. For instance, in one embodiment, the instrument108 may have a greater diameter than the instrument 132, permitting itto slide over both instruments 130 and 132 and into a position near thestenosis 128. Once positioned, the instrument 108 may collect medicaldata associated with the vessel 124 using an IVUS sensor. During amulti-modality procedure, the collection of IVUS data may occurconcurrently or subsequently to any collection of data with instruments130 and 132. It is understood that the instruments 130 and 132 may besized and shaped to allow any number of additional instruments to bepositioned within the vessel 124 during a multi-modality procedure.

Referring now to FIG. 4, illustrated is a diagrammatic, schematic viewof portions of the medical system 100 according to aspects of thepresent disclosure. As shown, in addition to the intravascularinstruments 108 and 110, the medical system 100 includes the externalimaging system 117, as discussed above. The external imaging system maygenerate diagnostic images such as x-ray images, angiogram images, CTimages, PET images, PET-CT images, MRI images, SPECT images, and/orother extraluminal diagnostic images, and such images may beco-registered with the internal-based diagnostic data and imagesgenerated by the intravascular instruments 108 and 110. The medicalsystem 100 includes also an instrument 152. In that regard, in someinstances instrument 152 is suitable for use as at least one ofinstruments 130 and 132 discussed above. Accordingly, in some instancesthe instrument 152 includes features similar to those discussed abovewith respect to instruments 130 and 132 in some instances. In theillustrated embodiment, the instrument 152 is a guide wire having adistal portion 154 and a housing 156 positioned adjacent the distalportion. In that regard, the housing 156 is spaced approximately 3 cmfrom a distal tip of the instrument 152. The housing 156 is configuredto house one or more sensors, transducers, and/or other monitoringelements configured to obtain the diagnostic information about thevessel. The housing 156 may contain a pressure sensor configured tomonitor a pressure within a lumen in which the instrument 152 ispositioned. A shaft 158 extends proximally from the housing 156. Atorque device 160 is positioned over and coupled to a proximal portionof the shaft 158. A proximal end portion 162 of the instrument 152 iscoupled to a connector 164. A cable 166 extends from connector 164 to aconnector 168. In some instances, connector 168 is configured to beplugged into an interface 170. In that regard, interface 170 is apatient interface module (PIM) in some instances. In some instances, thecable 166 is replaced with a wireless connection. In that regard, it isunderstood that various communication pathways between the instrument152 and the interface 170 may be utilized, including physicalconnections (including electrical, optical, and/or fluid connections),wireless connections, and/or combinations thereof. The interface 170 iscommunicatively coupled to the multi-modality processing system 101 viaa connection 174.

Together, connector 164, cable 166, connector 168, interface 170, andconnection 174 facilitate communication between the one or more sensors,transducers, and/or other monitoring elements of the instrument 152 andthe processing system 101. However, this communication pathway isexemplary in nature and should not be considered limiting in any way. Inthat regard, it is understood that any communication pathway between theinstrument 152 and the processing system 101 may be utilized, includingphysical connections (including electrical, optical, and/or fluidconnections), wireless connections, and/or combinations thereof. In thatregard, it is understood that the connection 174 is wireless in someinstances. In some instances, the connection 174 includes acommunication link over a network (e.g., intranet, internet,telecommunications network, and/or other network). In that regard, it isunderstood that the processing system 101 is positioned remote from anoperating area where the instrument 152 is being used in some instances.Having the connection 174 include a connection over a network canfacilitate communication between the instrument 152 and the remoteprocessing system 101 regardless of whether the processing system is inan adjacent room, an adjacent building, or in a different state/country.Further, it is understood that the communication pathway between theinstrument 152 and the processing system 101 is a secure connection insome instances. Further still, it is understood that, in some instances,the data communicated over one or more portions of the communicationpathway between the instrument 152 and the processing system 101 isencrypted.

The medical system 100 also includes an instrument 175. In that regard,in some instances instrument 175 is suitable for use as at least one ofinstruments 130 and 132 discussed above. Accordingly, in some instancesthe instrument 175 includes features similar to those discussed abovewith respect to instruments 130 and 132 in some instances. In theillustrated embodiment, the instrument 175 is a catheter-type device. Inthat regard, the instrument 175 includes one or more sensors,transducers, and/or other monitoring elements adjacent a distal portionof the instrument configured to obtain the diagnostic information aboutthe vessel. Instrument 175 may include a pressure sensor configured tomonitor a pressure within a lumen in which the instrument 175 ispositioned. The instrument 175 is in communication with an interface 176via connection 177. In some instances, interface 176 is a hemodynamicmonitoring system or other control device, such as Siemens AXIOM Sensis,Mennen Horizon XVu, and Philips Xper IM Physiomonitoring 5. In oneparticular embodiment, instrument 175 is a pressure-sensing catheterthat includes fluid column extending along its length. In such anembodiment, interface 176 includes a hemostasis valve fluidly coupled tothe fluid column of the catheter, a manifold fluidly coupled to thehemostasis valve, and tubing extending between the components asnecessary to fluidly couple the components. In that regard, the fluidcolumn of the catheter is in fluid communication with a pressure sensorvia the valve, manifold, and tubing. In some instances, the pressuresensor is part of interface 176. In other instances, the pressure sensoris a separate component positioned between the instrument 175 and theinterface 176. The interface 176 is communicatively coupled to theprocessing system 101 via a connection 178.

Similar to the connections between instrument 152 and the processingsystem 101, interface 176 and connections 177 and 178 facilitatecommunication between the one or more sensors, transducers, and/or othermonitoring elements of the instrument 175 and the processing system 101.However, this communication pathway is exemplary in nature and shouldnot be considered limiting in any way. In that regard, it is understoodthat any communication pathway between the instrument 175 and theprocessing system 101 may be utilized, including physical connections(including electrical, optical, and/or fluid connections), wirelessconnections, and/or combinations thereof. In that regard, it isunderstood that the connection 178 is wireless in some instances. Insome instances, the connection 178 includes a communication link over anetwork (e.g., intranet, internet, telecommunications network, and/orother network). In that regard, it is understood that the processingsystem 101 is positioned remote from an operating area where theinstrument 175 is being used in some instances. Having the connection178 include a connection over a network can facilitate communicationbetween the instrument 175 and the remote processing system 101regardless of whether the processing system is in an adjacent room, anadjacent building, or in a different state/country. Further, it isunderstood that the communication pathway between the instrument 175 andthe processing system 101 is a secure connection in some instances.Further still, it is understood that, in some instances, the datacommunicated over one or more portions of the communication pathwaybetween the instrument 175 and the processing system 101 is encrypted.

It is understood that one or more components of the medical system 100are not included, are implemented in a different arrangement/order,and/or are replaced with an alternative device/mechanism in otherembodiments of the present disclosure. For example, in some instances,the medical system 100 does not include interface 170 and/or interface176. In such instances, the connector 168 (or other similar connector incommunication with instrument 152 or instrument 175) may plug into aport associated with processing system 101. Alternatively, theinstruments 108, 110, 152, and 175 may communicate wirelessly with theprocessing system 101. Generally speaking, the communication pathwaybetween either or both of the instruments 108, 110, 152, and 175 and theprocessing system 101 may have no intermediate nodes (i.e., a directconnection), one intermediate node between the instrument and theprocessing system, or a plurality of intermediate nodes between theinstrument and the processing system.

Additionally, the instruments 108, 110, 152, and 175 may be sized andshaped to allow concurrent positioning of additional catheter-typeinstruments within a vessel. For instance, in one embodiment, theinstrument 108 may have a greater diameter than the instrument 175,permitting it to slide over both instruments 152 and 175 and into aposition near a position of interest within a vessel. In turn, theinstrument 110 may have a diameter greater than the instrument 108,permitting it to slide over instruments 108, 152 and 175. Oncepositioned, the instruments 108 and 110 may collect medical data usingIVUS, IVPA, OCT, intravascular MRI, and/or another type of imagingsensors concurrently or subsequently to any collection of data withinstruments 130 and 132. During such a multi-modality procedure, spatialco-registration of different types of data may be carried out in variousmanners. And, during a subsequent single or multi-modality procedure,spatial co-registration may be performed with the data collected in theprevious procedure and the data collected in the subsequent procedure.In that regard, the figures below illustrate various manners in which totemporally and spatially co-register single and multi-modalitydiagnostic data.

Diagnostic information within a vasculature of interest can be obtainedusing one or more of instruments 108, 110,130, 132, 152, and 175, aswell as external imaging system 117. For example, diagnostic informationis obtained for one or more coronaries arteries, peripheral arteries,cerebrovascular vessels, etc. The diagnostic information can includepressure-related values, flow-related values, diagnostic images ofintravascular portions of the patient, etc. Pressure-related values caninclude FFR, Pd/Pa (e.g., a ratio of the pressure distal to a lesion tothe pressure proximal to the lesion), iFR (e.g., a pressure ratio valuecalculated using a diagnostic window relative to a distance as a firstinstrument is moved through a vessel relative to a second instrument,including across at least one stenosis of the vessel), etc. Flow-relatedvalues can include coronary flow reserve or CFR (e.g., maximum increasein blood flow through the coronary arteries above the normal restingvolume), basal stenosis resistance index (BSR), etc.

In some embodiments, the diagnostic information obtained by the externalimaging system 117 can include externally-obtained angiographic images,x-ray images, CT images, PET images, MRI images, SPECT images, and/orother two-dimensional or three-dimensional extraluminal depictions of apatient's vasculature. The diagnostic information and/or data obtainedby instruments 108, 110, 130, 132, 152, and/or 175 are correlated orco-registered to angiographic image(s) and/or other two-dimensional orthree-dimensional depictions of a patient's vasculature obtained by theexternal imaging system 117. Spatial co-registration can be completedusing techniques disclosed in U.S. Pat. No. 7,930,014, titled “VASCULARIMAGE CO-REGISTRATION,” which is hereby incorporated by reference in itsentirety, based on the known pullback speed/distance, based on a knownstarting point, based on a known ending point, and/or combinationsthereof. In some embodiments, diagnostic information and/or data iscorrelated to vessel images using techniques similar to those describedin U.S. patent application Ser. No. 14/144,280 published as U.S. PatentApplication Publication No. 2014/0187920 on Jul. 3, 2014, which ishereby incorporated by reference in its entirety. In some embodiments,co-registration and/or correlation can be completed as described in U.S.patent application Ser. No. 14/335,603 published as U.S. PatentApplication Publication No. 2015/0025330 on Jan. 22, 2015, which ishereby incorporated by reference in its entirety. In other embodiments,co-registration and/or correlation can be completed as described inInternational Application No. PCT/IL2011/000612 published asWO2012/014212 on Feb. 2, 2012, which is hereby incorporated by referencein its entirety. Further, in some embodiments, co-registration and/orcorrelation can be completed as described in International ApplicationNo. PCT/IL2009/001089 published as WO2010/058398 on May 27, 2010, whichis hereby incorporated by reference in its entirety. Additionally, inother embodiments, co-registration and/or correlation can be completedas described in U.S. patent application Ser. No. 12/075,244 published asU.S. Patent Application Publication No. 2008/0221442 on Sep. 11, 2008,which is hereby incorporated by reference in its entirety.

Referring now to FIGS. 5-8, illustrated are a stylized images of aportion of a patient's vasculature according to embodiments of thepresent disclosure. One of ordinary skill in the art would recognizethat the images of FIGS. 5-8 are simply examples, and the intravascularelements depicted in FIGS. 5-8 may correspond to any bloodvessel—coronary, systemic, pulmonary, or otherwise—in a patient.Further, FIGS. 5-8 may be displayed on a display of a system assessing apatient's vasculature, such as display 118 and/or display 122 associatedwith the processing system 101 (FIGS. 1, 4). That is, one or morecomponents (e.g., a processor, processing circuit, and/or dedicatedgraphics processor, etc.) of the system 101 may cause the display of theimages shown in FIGS. 5-8.

In more detail, FIG. 5 illustrates three extraluminal images 200, 202,and 204 of a vessel 206 at three different times: time 0, time 1, andtime 2. The extraluminal images 200, 202, and 204 may be generated bythe external imaging system 117 (FIGS. 1, 4) and may be angiographicimages, x-ray images, CT images, PET images, MRI images, SPECT images,and/or other two-dimensional or three-dimensional depictions of thepatient's vasculature. The extraluminal images 200, 202, and 204 may allbe associated with the same extraluminal imaging modality or they may beassociated with different extraluminal imaging modalities. The points intime represented by time 0, time 1, and time 2 may be any threesuccessive points in time. For instance, they may be three points duringthe course of a longitudinal study that a practitioner deems useful inevaluating the physiological condition of the patient's vasculature. Inone embodiment, the longitudinal study may assess the effectiveness of amedical procedure performed before or during the study. The medicalprocedure may be an invasive procedure such as the insertion of anintravascular stent or it may be a non-invasive procedure such as theadministration of a drug. Additionally, the extraluminal images 200,202, and 204 include an arrow 208 that points to an area of interest inthe vessel 206. In the illustrated embodiment, the area of interestincludes a stenosis that is generally representative of any blockage orother structural arrangement that results in a restriction to the flowof fluid through the vessel 206.

As mentioned above, the extraluminal image 200 was captured at time 0,which, in the illustrated embodiment, represents a point in time beforean intravascular procedure was performed on the vessel 206 to treat thestenosis. The extraluminal image 202 was captured at time 1, whichrepresents a point in time subsequent to the intravascular procedurebeing performed on the vessel 206. Minutes, hours, days, weeks, months,or years may have passed between time 0 and time 1. In the illustratedembodiment, the vessel 206 shows fewer signs of blockage in the area ofinterest at time 1. In one embodiment, the extraluminal image 202 wascaptured immediately after the insertion of a stent during the course ofthe intravascular procedure. In another embodiment, the extraluminalimage 202 was captured during a follow-up visit subsequent to theintravascular procedure. The extraluminal image 204 was captured at time2, which represents a point in time subsequent to time 1. Minutes,hours, days, weeks, months, or years may have passed between time 1 andtime 2. In one embodiment, the extraluminal image 204 was capturedduring a first or subsequent follow-up visit after the intravascularprocedure. Although, FIG. 5 depicts three extraluminal images capturedat three points in time, a greater or fewer number of extraluminalimages may be captured at greater or fewer number of points in time.

In one embodiment, the extraluminal images 200, 202, and 204 aredisplayed concurrently on a display associated with the processingsystem 101 so that a practitioner may evaluate any changes in thephysiological condition of the vessel 206 over time. Spatialco-registration may be performed on the extraluminal images 200, 202,and 204 so that the same portions of the patient's vasculature aredisplayed in each of the extraluminal images. Such spatialco-registration positionally aligns the extraluminal images 200, 202,and 204 whether they are all associated with the same imaging modality(e.g., CT) or whether they are associated with two or more differentimaging modalities (e.g., CT and PET). In some embodiments, spatialco-registration may be performed so as to place the area of interest inthe vessel 206—as pointed to by the arrow 208—at the same relativeposition in each of the extraluminal images 200, 202, and 204. Placingthe area of interest in the same position—such as the center—in each ofthe extraluminal images 200, 202, and 204 may allow a practitioner toevaluate changes in the physiological condition of the vessel 206 in amore efficient manner. Such co-registration may be accomplished usingone or more of the co-registration techniques incorporated by referenceabove.

Referring now to FIG. 6, illustrated is a composite extraluminal image210 according to an embodiment of the present invention. Specifically,the extraluminal image 210 depicts a combination of the extraluminalimage 200 and the extraluminal image 202 from FIG. 5. A solid line 212represents the outline of the vessel 206 as depicted in the extraluminalimage 200 captured at time 0, and the broken line 214 represents theoutline of the vessel 206 as depicted in the extraluminal image 202captured at time 1. In the illustrated embodiment, the extraluminalimages 200 and 202 have been spatially aligned using co-registrationtechniques, such as those co-registration techniques discussed aboveand/or those incorporated by reference. In some embodiments, theprocessing system 101 may automatically (i.e., without humanintervention) co-register two or more images using one or moreco-registration algorithms implemented in software and/or hardware.After co-registration, the composite extraluminal image 210 may begenerated by the processing system 101 and visually output on a displayso that a practitioner may evaluate any changes in the physiologicalcondition of the vessel 206 over time.

As shown in the composite extraluminal image 210, the solid line 212 ofthe extraluminal image 200 and the broken line 214 of the extraluminalimage 202 are substantially aligned for a majority of patient'svasculature depicted in the extraluminal image 210. However, at the areaof interest in the vessel 206 pointed to by the arrow 208, the lines 210and 212 diverge, indicating that some physiological change has happenedto the vessel between time 0 and time 1. In the illustrated example, theperformance of an intravascular procedure between time 0 and time 1 haslessened the severity of a stenosis. That is, the vessel lumen is widerat time 1 than at time 0, as shown by the composite extraluminal image210. In this manner, by spatially co-registering the extraluminal image200 and the extraluminal image 202 and displaying a composite on adisplay device, a practitioner can quickly visually identify the changesin a patient's physiological condition and determine if theintravascular procedure was successful.

In additional embodiments, more than two images of a patient'svasculature may be co-registered and combined into a composite image fordisplay to a practitioner. In that regard, two or three or four or moreimages may be registered to a common time point, such as time 0.Additionally, in some embodiments, the processing system 101 mayautomatically determine any change in the physiological condition of thevessel 206 based on an automated analysis of the composite extraluminalimage 210. In that regard, after such analysis, the processing system101 may output a textual and/or graphical report highlighting anychanges in the physiological condition of the vessel for considerationby a practitioner. The processing system 101 may include software and/orhardware modules configured to perform such analysis.

Referring now to FIGS. 7 and 8, illustrated are three endoluminal images220, 222, and 224 of the vessel 206 at three different times: time 0,time 1, and time 2. The endoluminal images 220, 222, and 224 may begenerated by using one or more of the catheter-based instruments 108,110,130, 132, 152, and 175 (FIGS. 1, 4) and may be IVUS images, FL-IVUSimages, IVPA images, OCT images, NIRS images, or intravascular MRIimages, and/or other two-dimensional or three-dimensional depictions ofthe patient's vasculature captured from within the patient'svasculature. The endoluminal images 220, 222, and 224 may all beassociated with the same endoluminal imaging modality or they may beassociated with different endoluminal imaging modalities. The points intime represented by time 0, time 1, and time 2 may be any threesuccessive points in time, such as the points in time described inassociation with FIGS. 5 and 6 that are deemed significant in alongitudinal study. In the illustrated embodiment, endoluminal images220, 222, and 224 depict an area of interest of the vessel 206 thatincludes a stenosis generally representative of any blockage or otherstructural arrangement that results in a restriction to the flow offluid through the vessel. The area of interest shown in FIG. 6 may bethe same area of interest as pointed to by the arrow 208 in FIG. 5. Asshown in the endoluminal images 220, 222, and 224, the vessel 206includes a lumen 226 configured to allow the flow of fluid through thevessel.

The endoluminal image 220 was captured at time 0, which, in theillustrated embodiment, represents a point in time before anintravascular procedure was performed on the vessel 206 to remove thestenosis. The endoluminal image 222 was captured at time 1, whichrepresents a point in time subsequent to the intravascular procedurebeing performed on the vessel 206. In the illustrated example, a stent228 has been placed in the lumen 226 as part of the intravascularprocedure. Minutes, hours, days, weeks, months, or years may have passedbetween time 0 and time 1. At time 1, as compared to time 0, the lumen228 has a larger diameter, indicating that the intravascular procedurewas generally successful. In one embodiment, the endoluminal image 222was captured immediately after the insertion of the stent 228 during thecourse of the intravascular procedure. In another embodiment, theendoluminal image 222 was captured during a follow-up visit after theintravascular procedure. The endoluminal image 224 was captured at time2, which represents a point in time subsequent to time 1. Minutes,hours, days, weeks, months, or years may have passed between time 1 andtime 2. In one embodiment, the endoluminal image 224 was captured duringa first or subsequent follow-up visit after the intravascular procedure.Although FIG. 7 depicts three endoluminal images captured at threepoints in time, a greater or fewer number of endoluminal images may becaptured at greater or fewer number of points in time.

Additionally, although FIG. 7 depicts several points in time during alongitudinal study meant to assess the effectiveness of a stent, thelongitudinal study may alternatively assess the effectiveness of anon-invasive procedure. For example, a drug to reduce the stenosis mayhave been administered sometime before or during the time spanrepresented by times 0, 1, and 2, and the endoluminal images may allow apractitioner to evaluate whether the stenosis was affected by theadministration of the drug.

In one embodiment, the endoluminal images 220, 222, and 224 may bedisplayed concurrently on a display associated with the processingsystem 101 so that a practitioner may evaluate any changes in thephysiological condition of the vessel 206 over time. Spatialco-registration may be performed on the endoluminal images 220, 222, and224 so that the same portions of the patient's vasculature are displayedin each of the endoluminal images. Such spatial co-registrationpositionally aligns the endoluminal images 220, 222, and 224 whetherthey are all associated with the same imaging modality (e.g., IVUS) orwhether they are associated with two or more different imagingmodalities (e.g., IVUS and OCT). In some embodiments, spatialco-registration may be performed so as to place a specific portion ofthe vessel 206 at the same relative position in each of the endoluminalimages 220, 222, and 224. Placing the same portion of the vessel—such asthe center—in the same position in each of the endoluminal images 220,222, and 224 may allow a practitioner to compare the condition of thevessel at the area of interest in a more efficient manner.

Referring now to FIG. 8, illustrated is a composite endoluminal image230 according to an embodiment of the present invention. Specifically,the endoluminal image 230 depicts a combination of the endoluminal image220 and the endoluminal image 222 from FIG. 7. A solid line 232represents the outline of the vessel 206 and lumen 226 as depicted inthe endoluminal image 220 captured at time 0, and the broken line 234represents the outline of the vessel 206 and lumen 226 as depicted inthe endoluminal image 222 captured at time 1. In the illustratedembodiment, the endoluminal images 220 and 222 have been spatiallyaligned using one or more of the co-registration techniques incorporatedby reference above. In some embodiments, the processing system 101 mayautomatically (i.e., without human intervention) spatially align two ormore images using one or more co-registration algorithms implemented insoftware and/or hardware. After co-registration, the compositeendoluminal image 230 may be generated by the processing system 101 andvisually output on a display so that a practitioner may evaluate anychanges in the physiological condition of the vessel 206 over time.

As shown in the composite endoluminal image 230, the solid line 232 ofthe endoluminal image 220 and the broken line 234 of the endoluminalimage 222 are substantially aligned with the regard to the outercircumference of the vessel 206. However, with regard to the lumen 226,the lines 232 and 234 diverge, indicating that some physiological changehas happened to the vessel between time 0 and time 1. In the illustratedexample, the performance of an intravascular procedure between time 0and time 1 has increased the diameter of the lumen 226, and thus,lessened the severity of a stenosis. In this manner, by spatiallyco-registering the endoluminal image 220 and the endoluminal image 222and displaying a composite on a display device, a practitioner canquickly visually access the change in a patient's physiologicalcondition and determine if the intravascular procedure was successful.

In additional embodiments, more than two endoluminal images of apatient's vasculature may be co-registered and combined into a compositeimage for display to a practitioner. Additionally, in some embodiments,the processing system 101 may automatically determine any change in thephysiological condition of the vessel 206 and lumen 226 based on anautomated analysis of the composite endoluminal image 230. In thatregard, after such analysis the processing system 101 may output atextual and/or graphical report highlighting any changes in thephysiological condition of the vessel for consideration by apractitioner. The processing system 101 may include software and/orhardware modules configured to perform such analysis.

Referring now to FIG. 9, illustrated is a simplified flow chart of amethod 250 of assessing the condition of a vessel over time (i.e., alongitudinal study of a vessel), according to embodiments of the presentdisclosure. Portions of the method 250 may correspond to the techniquesdiscussed in association with FIGS. 5-8, and may be performed withhardware and/or software components of the processing system 101. Method250 begins at block 252 where a first graphical diagnostic measurementof a portion of a patient's vasculature is captured at a first time. Theportion of a patient's vasculature captured may include an area ofinterest such as a vessel that includes some type of stenosis. The firstgraphical diagnostic measurement may be an image associated with anyendoluminal or extraluminal imaging modality, such as those described inassociation with FIGS. 5-8. The point in time at which the firstgraphical diagnostic measurement is captured may correspond to any pointin time in a longitudinal study. The point in time may be before anintravascular procedure is performed, during the course of anintravascular procedure, after an intravascular procedure, or anotherpoint in time deemed diagnostically significant. The method 250 thenproceeds to block 254 where a second graphical diagnostic measurement ofthe same portion of the patient's vasculature is captured at a secondtime subsequent to the first time. In one embodiment, the secondgraphical diagnostic measurement is an image associated with the sameimaging modality as associated with the first graphical diagnosticmeasurement. In other embodiments, the first and second graphicaldiagnostic measurements are associated with different imagingmodalities. Further, the first and second graphical diagnosticmeasurements may be captured by one or more imaging instruments and/orimaging systems described in association with FIGS. 1-8. The secondpoint in time may be another point in time in the longitudinal study. Inone embodiment, the first point in time is before an intravascularprocedure and the second point in time is after the procedure. In otherembodiments, the first and second times are both after an intravascularprocedure. Alternatively, the longitudinal study is simply designed tomonitor a patient's vasculature in the absence of an intravascularprocedure.

Next, the method 250 proceeds to block 256 where the first and secondgraphical diagnostic measurements are spatially co-registered. That is,the image of the patient's vasculature captured at the first time isspatially aligned with the image of the patient's vasculature capturedat the second time. The co-registration may be performed according toone or more of the co-registration techniques discussed above orincorporated by reference. In that regard, the processing system 101 mayperform the co-registration using co-registration algorithms implementedin hardware and/or software. In one embodiment, spatially co-registeringthe first and second graphical diagnostic measurements includesoverlaying the second graphical diagnostic measurement over the firstgraphical diagnostic measurement to form a composite image, as discussedin association with FIGS. 6 and 8. One of ordinary skill in the artwould recognize that the same techniques may be applied to co-registerand overlay more than two graphical diagnostic measurements and form acomposite image. In some cases, overlaying more than two graphicaldiagnostic measurements may allow a practitioner to better evaluate apatient.

The method 250 then continues to block 258 where a visual representationof the co-registered first and second graphical diagnostic measurementsis output on a display associated with the processing system 101. Insome embodiments, the visual representation is a composite image of thefirst and second graphical diagnostic measurements, as illustrated inFIGS. 6 and 8. In other embodiments, the visual representation includesthe first and second graphical diagnostic measurements arranged in anadjacent manner with the area of interest in the first and secondgraphical diagnostic measurements located in the same relative positionin each of the images. Then, at block 260, it is determined whetherthere is a physiological difference between the portion of the patient'svasculature at the first time and at the second time based on theco-registration of the first and second graphical diagnosticmeasurements. In one embodiment, a practitioner visually inspects thevisual representation of the co-registered first and second graphicaldiagnostic measurements to make such a determination. In otherembodiments, the processing system 101 automatically makes thedetermination using diagnostic algorithms that analyze the first andsecond graphical diagnostic measurements. In that regard, after anautomated determination, the processing system 101 may output a textualand/or graphical report highlighting any changes in the physiologicalcondition of the vessel for consideration by a practitioner.

Finally, the method 250 ends at block 262, where the physiologicalcondition of the patient's vasculature is evaluated based on thedetermined physiological difference. In some embodiments, thisevaluation may include determining whether a blood flow through a vesselhas improved between the point in time the first graphical diagnosticmeasurement was captured and the point in time the second graphicaldiagnostic measurement was captured. In that regard, such an evaluationof the physiological condition of the patient's vasculature may be partof a longitudinal study to measure the effectiveness of an intravascularprocedure, such as the placement of a stent within a lumen, theeffectiveness of a non-invasive procedure, such as the administration ofa drug, or the effectiveness of a combination of an invasive and anon-invasive procedure. In some embodiments, the evaluation in block 262may be performed by the processing system 101 with hardware and/orsoftware-based evaluation algorithms that analyze the determinedphysiological difference and provide a human-readable evaluation of thepatient's vessel.

In this manner, the method 250 displays co-registered image datacollected during the course of a longitudinal study for use by apractitioner in evaluating a patient. Because such image data has beenspatially co-registered, a practitioner may efficiently evaluate thecondition of a patient over time in a visual manner, which may lead tomore accurate diagnoses than evaluations based on numerical measurementsalone.

It should be recognized that the method 250 of assessing the conditionof a vessel over time may include different and/or additional steps, andthat one or more of the illustrated blocks may be performed in adifferent order. Examples of the anatomical structure to which theaforementioned co-registration of graphical diagnostic images capturedover time may be applied include a coronary vessel, a coronary lesion, avessel, a vascular lesion, a lumen, a luminal lesion, and/or a valve.One of ordinary skill in the art would recognize that the techniques ofmethod 250 may be applied to lumens of a subject's body other than bloodvessels (for example, a lumen of the gastrointestinal or respiratorytract). Additionally, any number of graphical diagnostic measurementsmay be utilized during the course of method 250 to assess the conditionof a vessel or other lumen.

Referring now to FIG. 10, illustrated is a graphical user interface(GUI) screen 300 configured to facilitate the multi-modality assessmentof a patient's vasculature over time, according to aspects of thepresent disclosure. Specifically, the GUI screen 300 includes aplurality of stylized images of a portion of a patient's vasculaturecaptured at different points in time and with multiple different imagingmodalities. One of ordinary skill in the art will recognize that theimages illustrated in FIG. 10 are simply examples, and the intravascularelements depicted may correspond to any blood vessel—coronary, systemic,pulmonary, or otherwise—in a patient. Further, the GUI screen 300 may bedisplayed on a display of a system assessing a patient's vasculature,such as display 118 and/or display 122 associated with the processingsystem 101 (FIGS. 1, 4). That is, one or more components (e.g., aprocessor, processing circuit, and/or dedicated graphics processor,etc.) of the system 101 may cause the display of the GUI screen 300.

In more detail, the GUI screen 300 includes a three-dimensional CTreconstruction 302 of a patient's heart 304. In the illustratedembodiment, the heart 304 includes the vessel 206 illustrated in FIGS.5-8. In some embodiments, the three-dimensional CT reconstruction 302may be rotated about a vertical axis, a horizontal axis, or anarbitrarily-chosen axis. In some implementations, the three dimensionalmodel is displayed adjacent to a corresponding two dimensional depictionof the vessel. In that regard, the GUI screen 300 also includes theextraluminal images 200, 202, and 204 previously illustrated in FIG. 5and the endoluminal images 220, 222, and 224 previously illustrated inFIG. 7. Notably, the extraluminal images 200, 202, and 204 are imagesassociated with a different imaging modality than the endoluminal images220, 222, and 224. For instance, the extraluminal images 200, 202, and204 may be angiographic images captured by the external imaging system117, and the endoluminal images 220, 222, and 224 may be IVUS imagescaptured by any of the catheter-based instruments 108, 110,130, 132,152, and 175 discussed above. The GUI screen 300 also includes aplurality of numerical measurements 306 associated with the portion ofthe patient's vasculature captured in the adjacent extraluminal andendoluminal images. The numerical measurements 306 were taken at thesame points in time as the extraluminal and endoluminal images (i.e.,time 0, time 1, and time 2). In the illustrated embodiment, thenumerical measurements 306 are iFR calculations (as described, forexample, in U.S. patent application Ser. No. 13/460,296, filed Apr. 30,2012, which is hereby incorporated by reference in its entirety)associated with a stenosis in the vessel 206, but, in alternativeembodiments, they may be other types of numerical measurements relatedto pressure and/or flow of blood through a vessel such as FFR, CFR, orBSR measurements.

In the GUI screen 300, extraluminal images 200, 202, and 204 have beenspatially co-registered such they depict the same portion of thepatient's vasculature over time. Similarly, endoluminal images 220, 222,and 224 have been spatially co-registered such they depict the sameportion of the patient's vessel 206 over time.

Additionally, the extraluminal image 200 captured at time 0 ispositioned adjacent to the endoluminal image 220 also captured at time0. In that regard, the extraluminal image 200 has been spatially andtemporally co-registered with the endoluminal image 220 so that theimages depict the same portion of the patient's vasculature at the sametime (i.e. at time 0). In this case, the images 200 and 220 both depictthe area of interest in the vessel 206 that includes a stenosis, asdescribed above. Further, as shown in FIG. 10, a numerical measurement308 is positioned adjacent the images 200 and 220. In that regard, thenumerical measurement 308 has been spatially and temporallyco-registered with the images 200 and 220, such that the numericalmeasurement 308 corresponds to the state of the vessel 206 at the timethe images 200 and 220 were captured. Similarly, extraluminal image 202captured at time 1 is positioned adjacent to the endoluminal image 222also captured at time 1. In that regard, the extraluminal image 202 hasbeen spatially and temporally co-registered with the endoluminal image222 so that the images depict the same portion of the patient'svasculature at the same time. Further, a numerical measurement 310adjacent the images 202 and 222 has been spatially and temporallyco-registered with the images, such that the numerical measurementcorresponds to the state of the vessel 206 as shown in the images 202and 222. Similarly, images 204 and 224 and a numerical measurement 312have been spatially and temporally co-registered.

In this manner, the GUI screen 300 displays co-registered multi-modalitydata collected during the course of one or more longitudinal studies.Because such multi-modality image data has been spatially and temporallyco-registered, a practitioner may efficiently evaluate the condition ofa patient over time in a visual manner, which may lead to more accuratediagnoses than evaluations based on numerical measurements alone.

Further, in the example embodiment of FIG. 10, the extraluminal images200, 202, and 204 and endoluminal images 220, 222, and 224 have beenspatially co-registered with the three-dimensional CT reconstruction302. In that regard, a practitioner may select an area of interest withthe arrow 208 and all available diagnostic data corresponding to theselected area is displayed in the GUI screen 300. In the illustratedexample, the portion of the vessel 206 selected by the arrow 208 in thethree-dimensional CT reconstruction 302 has been imaged usingangiographic and IVUS techniques over the course of a longitudinal studyspanning time 0 to time 2. An iFR, FFR, or other pressure-basedlongitudinal study corresponding to the area of interest in vessel 206is also available and thus displayed in GUI screen 300. In oneembodiment, the user may select both the type of depiction(s) (twodimensional (including imaging modality type) and/or three dimensional)along with what visualization mode(s) and/or portions thereof will beutilized. The system will output a corresponding display based on theuser's preferences/selections and/or system defaults. In someembodiments, two-dimensional image data may include multiple views abouta vertical axis such that different two-dimensional views are shown whenthe three-dimensional CT reconstruction 302 is rotated. While the visualrepresentations of FIG. 10 have been described in the context of asingle GUI screen 300, it is understood that a system may display anycombination of these visual representations in series, simultaneously,and/or combinations thereof. In some instances, a system provides theuser the ability to select which individual visual representation and/orcombination of visual representations will be displayed.

One of ordinary skill in the art would recognize that the GUI screen 300is simply an example and that such user interface screens may includeadditional and/or different graphical and textual components and controlelements. For instance, the GUI screen 300 may also include compositediagnostic images generated from two or more endoluminal or extraluminalimages captured over time, such as the composite images 210 and 230respectively illustrated in FIGS. 6 and 8. Such composite images mayallow a practitioner to more effectively identify changes in a patient'sphysiology over time. Additionally, one of ordinary skill in the artwould recognize that although three endoluminal images and threeextraluminal images have been co-registered on the GUI screen 300, thesame techniques may be applied to any number of endoluminal and/orextraluminal images. In some cases, displaying more than three images ofeach type may allow a practitioner to better evaluate a patient.

Referring now to FIG. 11, illustrated is a simplified flow chart of amethod 350 for assessing the condition of a vessel over time (i.e., alongitudinal study of a vessel), according to embodiments of the presentdisclosure. Portions of the method 350 may correspond to the techniquesdiscussed in association with FIGS. 5-8 and 10, and may be performedwith hardware and/or software components of the processing system 101.Method 350 begins at blocks 352 and 354 where first and second graphicaldiagnostic measurements of a portion of a patient's vasculature arecaptured at a first time. The portion of the patient's vasculaturecaptured may include an area of interest such as a vessel that includessome type of stenosis. The first and second graphical diagnosticmeasurements may be images associated with different imaging modalities.In one embodiment, the first graphical diagnostic measurement may be animage associated with an endoluminal imaging modality—such as IVUS, OCT,IVPA, intravascular MRI, thermal, ICE, TEE, TTE and/or other internalimaging techniques—and the second graphical diagnostic measurement maybe an image associated with an extraluminal imaging modality, such asx-ray, angiogram, CT, PET, PET-CT, MRI, SPECT, and/or otherexternal-based imaging modality. Further, the first and second graphicaldiagnostic measurements may be captured by one or more imaginginstruments and/or imaging systems described in association with FIGS.1-8. The point in time at which the first and second graphicaldiagnostic measurements are captured may correspond to any point in timein a longitudinal study. The point in time may be before anintravascular procedure is performed, during the course of anintravascular procedure, after an intravascular procedure, or anotherpoint in time deemed diagnostically significant. Note that, in someembodiments, the “point in time” at which the first and second graphicaldiagnostic measurements are captured may refer to a non-instantaneousblock of time. That is, a diagnostically-insignificant amount of timemay transpire between the capture of the first image and the capture ofthe second image in blocks 352 and 354. In one example, the first andsecond images may be captured sequentially during a diagnostic session.

The method 350 continues to blocks 356 and 358 where third and fourthgraphical diagnostic measurements of the same portion of the patient'svasculature is captured at a second time subsequent to the first time.The third graphical diagnostic measurement is an image associated withthe same imaging modality as associated with the first graphicaldiagnostic measurement, but may be captured with the same or a differentinstrument. Similarly, the fourth graphical diagnostic measurement is animage associated with the same imaging modality as associated with thesecond graphical diagnostic measurement, but may be captured with thesame or a different instrument. Further, the third and fourth graphicaldiagnostic measurements may be captured by one or more imaginginstruments and/or imaging systems described in association with FIGS.1-8. The second point in time may be another point in time in thelongitudinal study. In one embodiment, the first time is before anintravascular procedure and the second time is after the procedure. Inother embodiments, the first and second times are both after anintravascular procedure. Alternatively, the longitudinal study is simplydesigned to monitor a patient's vasculature in the absence of anintravascular procedure. Note that, in some embodiments, the “point intime” at which the third and fourth graphical diagnostic measurementsare captured may refer to a non-instantaneous block of time. That is, adiagnostically-insignificant amount of time may transpire between thecapture of the third image and the capture of the fourth image in blocks356 and 358. In one example, the third and fourth images may be capturedsequentially during a diagnostic session.

Next, in block 360, the first and third graphical diagnosticmeasurements are spatially co-registered. That is, the image of thepatient's vasculature captured at the first time in the first modalityis spatially aligned with the image of the patient's vasculaturecaptured at the second time in the same modality. In one embodiment,spatially co-registering the first and third graphical diagnosticmeasurements includes overlaying the third graphical diagnosticmeasurement over the first graphical diagnostic measurement to form acomposite image, as discussed in association with FIGS. 6 and 8.Similarly, in block 362, the second and fourth graphical diagnosticmeasurements are spatially co-registered. That is, the image of thepatient's vasculature captured at the first time in the second modalityis spatially aligned with the image of the patient's vasculaturecaptured at the second time in the same modality. In one embodiment,spatially co-registering the second and fourth graphical diagnosticmeasurements includes overlaying the fourth graphical diagnosticmeasurement over the second graphical diagnostic measurement to form acomposite image, as discussed in association with FIGS. 6 and 8. Theco-registration in blocks 360 and 362 may be performed according to oneor more of the co-registration techniques described in association withFIGS. 5-9 or incorporated by reference. In one embodiment, theprocessing system 101 may perform the co-registration usingco-registration algorithms implemented in hardware and/or software.

The method 350 next proceeds to block 364 where the first and secondgraphical diagnostic measurements are spatially and temporallyco-registered. In that regard, the image of the patient's vasculaturecaptured at the first time in the first modality is spatiallyco-registered with the image of the patient's vasculature also capturedat the first time but in the second modality. In one embodiment, thisspatial so-registration aligns an endoluminal image with an extraluminalimage. Further, the temporal co-registration between the first andsecond graphical diagnostic measurements ensures that the images depictthe portion of the patient's vasculature at the same time to enableaccurate diagnoses. In block 366, the third and fourth graphicaldiagnostic measurements are similarly spatially and temporallyco-registered. In that regard, the image of the patient's vasculaturecaptured at the second time in the first modality is spatially andtemporally aligned with the image of the patient's vasculature alsocaptured at the second time but in the second modality.

The method then continues to block 368 where visual representations ofthe co-registered first, second, third, and fourth graphical diagnosticmeasurements are output on a display associated with the processingsystem 101. In some embodiments, such as GUI screen 300 illustrated inFIG. 10, the visual representations include the first, second, third,and fourth graphical diagnostic measurements arranged in an adjacentmanner, where each image depicts the area of interest (e.g., a stenosisin a vessel) in the same relative position to aid diagnosis. In otherembodiments, the visual representations include a composite image of thefirst and third graphical diagnostic measurements (that are in the firstmodality) and a composite image of the second and fourth graphicaldiagnostic measurements (that are in the second modality).

Next, at block 370, it is determined whether there is a physiologicaldifference between the portion of the patient's vasculature at the firsttime and the second time based on the spatial and temporalco-registration of the first, second, third, and fourth graphicaldiagnostic measurements. In one embodiment, a practitioner visuallyinspects the visual representations of the spatially co-registered firstand third graphical diagnostic measurements, the spatially co-registeredsecond and fourth graphical diagnostic measurements, the spatially andtemporally co-registered first and second graphical diagnosticmeasurements, and spatially and temporally co-registered third andfourth graphical diagnostic measurements to make such a determination.In other embodiments, the processing system 101 automatically makes thedetermination using diagnostic algorithms that analyze the graphicaldiagnostic measurements. In that regard, after an automateddetermination, the processing system 101 may output a textual and/orgraphical report highlighting any changes in the physiological conditionof the vessel for consideration by a practitioner.

Finally, the method 350 ends at block 372, where the physiologicalcondition of the patient's vasculature is evaluated based on thedetermined physiological difference. In some embodiments, thisevaluation may include determining whether a blood flow thorough avessel has improved between the point in time the first and secondgraphical diagnostic measurements were captured and the point in timethe third and fourth graphical diagnostic measurements were captured. Inthat regard, such an evaluation of the physiological condition of thepatient's vasculature may be part of a longitudinal study to measure theeffectiveness of an intravascular procedure, such as the placement of astent within a lumen. In some embodiments, the evaluation in block 372may be performed by the processing system 101 with hardware and/orsoftware-based evaluation algorithms that analyze the determinedphysiological difference and provide a human-readable evaluation of thepatient's vessel.

In this manner, the method 350 displays spatially and temporallyco-registered image data collected during the course of a longitudinalstudy for use by a practitioner in evaluating a patient's physiologicalcondition. Because such image data has been spatially and temporallyco-registered, a practitioner may efficiently evaluate the condition ofa patient over time in a visual manner, which may lead to more accuratediagnoses than evaluations based on numerical measurements alone.

It should be recognized that the method 350 of assessing the conditionof a vessel over time may include different and/or additional steps, andthat one or more illustrated blocks may be performed in a differentorder. For instance, the method 350 may also include blocks related tocollecting numerical measurements—such as pressure and flowmeasurements/calculations—at the each of the first and second times.Such numerical measurements may then be temporally co-registered withthe graphical diagnostics measurements, such that determining anyphysiological difference in the patient is also based on theco-registered numerical measurements. Examples of the anatomicalstructure to which the aforementioned co-registration of graphicaldiagnostic images captured over time may be applied include a coronaryvessel, a coronary lesion, a vessel, a vascular lesion, a lumen, aluminal lesion, and/or a valve. One of ordinary skill in the art wouldalso recognize that the techniques of method 350 may be applied tolumens of a subject's body other than blood vessels (for example, alumen of the gastrointestinal or respiratory tract). Additionally, anynumber of graphical diagnostic measurements may be utilized during thecourse of method 350 to assess the condition of a vessel or other lumen.

Persons skilled in the art will recognize that the apparatus, systems,and methods described above can be modified in various ways.Accordingly, persons of ordinary skill in the art will appreciate thatthe embodiments encompassed by the present disclosure are not limited tothe particular exemplary embodiments described above. In that regard,although illustrative embodiments have been shown and described, a widerange of modification, change, and substitution is contemplated in theforegoing disclosure. It is understood that such variations may be madeto the foregoing without departing from the scope of the presentdisclosure. Accordingly, it is appropriate that the appended claims beconstrued broadly and in a manner consistent with the presentdisclosure.

What is claimed is:
 1. A method of evaluating a vessel of a patient,comprising: obtaining, at a first time, a first graphical diagnosticmeasurement of the vessel of the patient, the first graphical diagnosticmeasurement being in a first medical modality; obtaining, at a secondtime subsequent to the first time, a second graphical diagnosticmeasurement of the vessel, the graphical diagnostic measurement being inthe first medical modality; spatially co-registering the first andsecond graphical diagnostic measurements; outputting a visualrepresentation of the co-registered first and second graphicaldiagnostic measurements on a display; and determining a physiologicaldifference between the vessel at the first time and the vessel at thesecond time based on the co-registered first and second graphicaldiagnostic measurements to evaluate the physiological condition of thevessel of the patient.
 2. The method of claim 1, wherein anintravascular procedure was performed on the vessel between the firsttime and the second time.
 3. The method of claim 2, wherein theintravascular procedure includes inserting a stent into the vessel. 4.The method of claim 1, wherein spatially co-registering includesgenerating a composite diagnostic image by overlaying the secondgraphical diagnostic measurement on the first graphical diagnosticmeasurement.
 5. The method of claim 4, wherein outputting the visualrepresentation includes outputting the composite diagnostic image on thedisplay.
 6. The method of claim 4, wherein determining the physiologicaldifference is based on the composite diagnostic image.
 7. The method ofclaim 1, wherein determining a physiological difference includesvisually comparing a first depiction of the vessel in the firstgraphical diagnostic measurement and a second depiction of the vessel inthe second graphical diagnostic measurement.
 8. The method of claim 7,wherein the comparing includes comparing a first cross-sectional lumenarea of the vessel at a point of interest as depicted in the firstgraphical diagnostic measurement and a second cross-sectional lumen areaof the vessel at the point of interest as depicted in the secondgraphical diagnostic measurement.
 9. The method of claim 1, wherein thefirst graphical diagnostic measurement is an extraluminal image.
 10. Themethod of claim 9, wherein the first graphical diagnostic measurement isone of an x-ray image, an angiogram image, an ultrasound image, atwo-dimensional computed tomography (CT) image, a three-dimensional CTimage, a computed tomography angiogram (CTA) image, a positron emissiontomography (PET) image, a PET-CT image, a magnetic resonance image(MRI), and a single-photon emission computed tomography (SPECT) image.11. The method of claim 1, wherein the first graphical diagnosticmeasurement is an endoluminal image.
 12. The method of claim 11, whereinthe first graphical diagnostic measurement is one of an intravascularultrasound (IVUS) image, a forward looking IVUS (FL-IVUS) image, anintravascular photoacoustic (IVPA) image, a near-infrared Spectroscopy(NIRS) image, an optical coherence tomography (OCT) image, anintracardiac echocardiography (ICE) image, a forward-looking ICE (FLICE)image, and an intravascular magnetic resonance image (MRI).
 13. A systemof evaluating a vessel of a patient, comprising: an instrumentconfigured to obtain graphical diagnostic measurements of the vessel ofthe patient; a processing system in communication with the firstinstrument, the processing unit configured to: obtain, at a first time,a first graphical diagnostic measurement of the vessel from theinstrument, the first graphical diagnostic measurement being in a firstmedical modality; obtain, at a second time subsequent to the first time,a second graphical diagnostic measurement of the vessel from theinstrument, the graphical diagnostic measurement being in the firstmedical modality; spatially co-register the first and second graphicaldiagnostic measurements; output a visual representation of theco-registered first and second graphical diagnostic measurements on adisplay; and determine a physiological difference between the vessel atthe first time and the vessel at the second time based on theco-registered first and second graphical diagnostic measurements toevaluate the physiological condition of the vessel of the patient. 14.The system of claim 13, wherein an intravascular procedure was performedon the vessel between the first time and the second time.
 15. The systemof claim 14, wherein the intravascular procedure includes inserting astent into the vessel.
 16. The system of claim 13, wherein the system isfurther configured to generate a composite diagnostic image byoverlaying the second graphical diagnostic measurement on the firstgraphical diagnostic measurement.
 17. The system of claim 16, whereinthe system is further configured to output the composite diagnosticimage on the display.
 18. The system of claim 16, wherein the system isfurther configured to determine the physiological difference based onthe composite diagnostic image.
 19. The system of claim 13, wherein thefirst graphical diagnostic measurement is an extraluminal image.
 20. Thesystem of claim 19, wherein the first graphical diagnostic measurementis one of an x-ray image, an angiogram image, an ultrasound image, atwo-dimensional computed tomography (CT) image, a three-dimensional CTimage, a computed tomography angiogram (CTA) image, a positron emissiontomography (PET) image, a PET-CT image, a magnetic resonance image(MRI), and a single-photon emission computed tomography (SPECT) image.21. The system of claim 13, wherein the first graphical diagnosticmeasurement is an endoluminal image.
 22. The system of claim 13, whereinthe first graphical diagnostic measurement is one of an intravascularultrasound (IVUS) image, a forward looking IVUS (FL-IVUS) image, anintravascular photoacoustic (IVPA) image, a near-infrared Spectroscopy(NIRS) image, an optical coherence tomography (OCT) image, anintracardiac echocardiography (ICE) image, a forward-looking ICE (FLICE)image, and an intravascular magnetic resonance image (MRI).